You don't need to worry about calcium hardness.

Keep some chlorine in there so the pool doesn't turn green. It is amazing how fast that can happen. Until your stabilizer gets into the water, you'll need to test chlorine at least morning and evening (and afternoon if you are home) and probably add bleach each time. Once the CYA starts registering, then you'll be able to just test and dose chlorine in the evenings only.

You are right to wait before retesting CYA. No need to waste the reagent.

Looks like you are off to a good start!